Validation of a Combined Prognostic Score Using Plasma Tumor DNA and Clinical Features in Metastatic Castration-Resistant Prostate Cancer Patients Treated with Taxanes.

Purpose: There is an urgent need of biomarkers to personalize metastatic castration-resistant prostate cancer (mCRPC) treatment. A new prognostic model described by our group combines molecular characteristics (ptDNA levels), metabolic features from PET-scans (metabolic tumor volume), clinical parameters (visceral metastases), and lab tests (lactate-dehydrogenase levels) in abiraterone or enzalutamide-treated patients. This study aims to validate the score on mCRPC patients undergoing taxane treatment. Patients and Methods: Twenty-eight patients affected by mCRPC, pre-treated with abiraterone or enzalutamide, candidate for taxane-based treatments, have been prospectively evaluated. All patients underwent a basal PET/CT scan with F-choline and blood samples. The prognostic model previously described was applied to this population; based on the partial results of the parameters, we assigned the patients into three risk groups. Results: In the 28 patients evaluated, we observed a different median OS among the three risk groups (risk group I, 18.1 months [95% CI: 15.2-33.1 months]; risk group II, 12.7 months [4.9-18.6 months]; and risk group III, 10.1 months [3.4-15.4 months]; p = 0.012). Statistically significant differences were also observed for PFS. Conclusion: The prognostic score has confirmed to be a good prognostic tool also in a more advanced cohort of patients treated with taxanes. This tool may represent a valid method to refine prognostication and treatment selection in a cohort of patients where biomarkers are scarce.